1. Field of the Invention
The present invention relates to a method of washing clothing articles and, more particularly, to a high performance method of washing clothing articles in a vertical axis automatic washer that includes a concentrated detergent solution washing operation.
2. Description of the Prior Art
Prior art washing machines use various different methods for washing clothes loads but, in general, all methods utilize varying amounts of mechanical, chemical, and thermal energy to remove soil from the fabric. Many machines employ an agitator that is mounted on a vertical axis and driven in an oscillating rotary fashion to agitate the clothes load in the presence of a detergent solution. After a predetermined period of agitation, such a wash cycle is typically followed with a rinse cycle. By way of example, conventional methods for washing a six pound "normal" load of mixed cotton and polyester fabric in a vertical axis washer typically include twelve to fourteen minutes of agitation in a wash bath having a volume of about 64 liters of water, resulting in a water to cloth ratio of approximately twenty-four to one (by weight). Detergent concentrations within the range of 0.06% to 0.28% are typically used during such washing operations, the detergent concentration being defined as the percent by weight of detergent for unit volume of water.
Some prior art wash methods wash the clothes load in a concentrated detergent solution for the purpose of enhancing soil removal or reducing the amount of water consumed during the washing operation. Such concentrated wash methods have been most commonly employed on horizontal axis washing machines which provide mechanical agitation of the clothes load by tumbling the load during the concentrated washing operation. U.S. Pat. No. 4,489,574 describes such a concentrated wash process. One prior art method is known for conducting a concentrated washing operation in a vertical axis washer of the type disclosed in U.S. Pat. No. 4,225,992. This process is, however, limited to small wash loads and requires the use of a separate, auxiliary wash basket.
The known prior art wash methods, whether practiced in a horizontal axis or a vertical axis machine, employ varying amounts of mechanical agitation of the clothes load. That is, during the concentrated washing operation the individual items of clothing are moved relative to each other and relative to the wash basket or drum. While such agitation of the clothes load is generally desirable in achieving good soil removal, agitation of the clothes load is also known to cause various types of fabric damage. The amount of fabric damage that occurs during a washing operation is a function of many variables, including the duration and type of agitation provided, the type of fabric being washed, and the amount of water in the wash bath. The damage most commonly experienced includes abrasion, pilling, and deformation due to stretching, tangling, etc.